REVISION IN PROGRESS – DECEMBER 2011

Early Electric Pick-ups for 78 rpm Records.

Some notes, jotting & reminiscences.

Some of the items described below came from the collection of the late Ron Armstrong, which covered all aspects of early sound reproduction.

I never knew him, but would like to dedicate this web-page to his memory.

A group of electric pick-ups, all from the Ron Armstrong Collection. Clockwise from top left: 1. ‘AED’. Single coil, bakelite casing. 2. ‘HEGRA’. Single coil, nickel-plated metal casing. 3. ‘DAPTACON’. Single coil, metal casing, brown finish. 4. ‘J.B. Woodroffe’. Uncased, magnet and mount nickel-plated. The interior structure of 1 & 2 is illustrated below. (The Daptacon is misplaced here; it appears again, in its proper place, further down the page.)

Electrical recording on disc, as we all know, became truly practical when Western Electric in the U.S.A. threw a lot of money at the question, in the early 1920s, in order to make still more of it. There had been previous electrical recordings of course: after all, there is hardly anything new under the sun. But W.E., with their corporate resources, made it work very well indeed. It was introduced, quite subtly, by the major labels Victor & Columbia, in 1925. Subtly of course, because they didn’t want to make their existing catalogues obsolete overnight; they needed time to gradually remake all their best-selling acoustic recordings by the new system.

Still, electrical reproduction was the next most obvious thing to go for. Generally, U.S. Brunswick with their ‘Panatrope’ is credited with developing the first practical electric gramophone in 1926. It was state of the art, and naturally, very expensive. I have no idea what sort of pick-up it had.

But before we launch into the main subject of this page, it will be useful to review the origins of turning mechanical vibrations into electricity, and back again. When Alexander Graham Bell perfected the telephone in 1876, it relied on the very simple – and therefore elegant – concept that magnetism could be converted into electric current – and vice versa. I think Michael Faraday had shown this, maybe half a century before. In its simplest form then, the telephone, if spoken into, would convert the vibrations of the speech falling on a thin flat diaphragm of iron, into a small electrical voltage. And at the other end of the wires, an exactly similar device would convert that small voltage back into sound, by activating the diaphragm of the receiver. Thus, you had one device that could act as a sender and a receiver. Of course, the range of this original telephone system was quite limited, and soon the function of sender and receiver were separated, and a more specialised device was used as the sender – or microphone, as it eventually became. But as regards the ‘receiver’, this remained the same for very many decades. The voltage, arriving, passed through a coil – or coils – of fine wire, and caused varying magnetism in the metal core around which those coils were wound. This magnetic field made to vibrate a thin iron diaphragm, which reproduced the original sound. When I was young back in the 1940s & 1950s, our telephones in the U.K. had exactly the same ‘receiver’ as had been devised back in the 1870s!

The ‘headphones’ of the early radio broadcasting era, which started in the UK in late 1922, naturally worked on the same principle. Here are some photos. of such a pair of headphones, which date from no later than 1927. They were made by the General Electric Company.

First shot, the headphones themselves. Second, one receiver. Third, the receiver with the ebonite earpiece unscrewed. Fourth, the inside of the receiver with the flat iron diaphragm taken off. (You slid the diaphragm off, never pulled it off. Doing that would diminish the magnetism in the core!) Observe the two coils, wrapped in green tape, placed round the thin magnetic core: these will become very familiar to us as this page grows. Why two coils? Why not just one? Well, the magnetism induced in the iron core by the tiny voltage, comes out at both ends of it. So if we only had one coil, only one end of it would be near the diaphragm to make the sound. The magnetism, the precious energy, coming out of the other end would be lost. So, the core was bent round into a ‘U’ shape, so that both ends of it were near the diaphragm, thus making best use of the energy. This also involved winding each coil in the opposite direction or ‘sense’: but that’s not important right now.

What is important, is that headphones like this had been around for a long time. And so, experimenters would have tinkered around with them and used them for other purposes. These headphones were quite expensive, mostly because those little coils had many thousands of turns of very fine wire on them & so were tedious to make. But, as War Surplus after the Great War of 1914-1918, I dare say they became rather less expensive. And so, it must have occurred to a number of people, to use them as electrical reproducers of records. The most obvious candidate would be cylinder records, as they were recorded with an ‘up-and-down’ motion – vertically cut. It would have been a fairly simple matter to take an ear-piece as above, and place a sapphire or glass stylus in the middle of the diaphragm, then position the earpiece in place of the acoustic ‘reproducer’ those phonographs used. But: what would one do then? What would one do with the tiny signal that came out of your newly-invented electrical earpiece-reproducer? Well, one might listen to it on a pair of headphones. But this would have been a retrograde step. Phonograph cylinders had been listened to using an acoustic stethoscope type of device back in the 1890s… Our intrepid inventor would have needed to amplify his tiny signal and feed it into a loudspeaker in order to attain really effective electrical reproduction. Alas, just after the end of the Great War, there were still restrictions on the use of the newly-developed valves (tubes) which could amplify sound: and in any case, valves being ‘cutting edge technology’, were very expensive. Moreover, even loudspeakers themselves were still in their infancy, usually consisting merely of an assembly as shown above right, coupled into a straight or curved horn to amplify the signal acoustically. Still, I don’t doubt that some people explored these elusive avenues in 1918 onwards. And they were the first pioneers of electrical reproduction!

Now let us look at some of these devices. I think we need two fundamental ‘classes’, as follows:

Class 1a. Electric pick-ups with pillar terminals, sold as ‘add-on’ devices to existing acoustic gramophones.

Class 1b. Electric pick-ups with a flying lead, sold as ‘add-on’ devices to existing acoustic gramophones.

Class 2. Electric pick-ups that came with their own arm, which would entirely replace the tone arm of the acoustic gramophone.

In the earliest days, i.e. the later 1920s, Class 1 pick-ups naturally predominated.

Class 1a pick-ups.

In early 1927, a patent specification was drawn up in London for an electrical pick-up, developed by J. B. Woodroffe, sold by the firm of J. Glasscoe & Co., and illustrated above. It was a most successful design, and by September that year, had been adopted by the BBC. Previously the BBC had, perforce, to place a microphone near the horn of an acoustic machine. You will immediately recognise the two coils of wire, wound around a ‘U’ shaped piece of iron securely fastened to the left arm of a horse-shoe magnet. These two simple elements – a coil and a magnet – form the basis of almost all the early electrical pick-ups made from the later 1920s until well into the 1930s. By the way, though the Woodroffe was well reviewed in ‘The Gramophone’ and taken up by the BBC, they were very expensive at £3 15s – far more than a week’s wages for most people.

How did they work? We begin, naturally, with our Class 1 pick-ups, the ones you fitted to the arm of an existing gramophone. (Only three of the four pick-ups illustrated at the top of this page are Class 1. The fourth, the ‘Daptacon’, was included because it seemed to belong there. We have since obtained a complete ‘Daptacon’ arm, and it actually is a Class 2 device, and so is dealt with in its proper place, below.)

On the left is a typical, budget-price acoustic spring-driven gramophone, probably circa 1925. One simply removed the sound-box and replaced it with the electric pick-up. A pair of wires, typically standard twisted ‘flex’, was connected to the two nickel-plated pillar terminals: coaxial cable was a rarity at the time. The signal was fed into your radio set – more on that later. Several different sizes of tone arm were in use, so an adaptor bush was often needed; alternatively, as you will see below, the socket on the pickup was often made adjustable.

Here are 6 more Class 1a pick-ups. Each will be discussed below. 1: A brightly chromium plated BTH, with a ‘castellated’ mounting socket. 2: A Lissen with an aluminium case. 3: The S.G. Brown GPU No.2. 4: The Burndept. 5: An incomplete pick-up; alas, the front is missing and would doubtless have given the manufacturer’s name. 6. The ‘Ajax’ four-pole pick-up. All of these, as well as the Woodroffe above, are still in working order except, obviously, No.5.

1. This BTH (British Thompson-Houston) is a classic single coil design which was repeated for years by many different makers, possibly under licence. The armature A – the moving element oscillated by the needle in the groove – is pivoted between the pole pieces P by two small rubber tube suspensions, which have disintegrated in this item as usual after 70 – 80 years. The rest of the armature passes up through the coil C, and then goes between the tiny gap in the upper parts of the pole pieces. It is at this point that the lateral movement of the armature induces a current into the coil. Finally, the top of the armature, which is flattened and often called the ‘fish-tail’, passes into D, a rubber block which both supports it vertically and damps out any mechanical resonance – more on resonance below. The rear of the pick-up has the pillar terminals for the connecting wire, and helpfully tells us that the patent for this item was applied for in 1929. BTH continued to make this pick-up for some years. It is actually found more frequently ‘all of a piece’ with its BTH pick-up arm, illustrated below. The DC resistance of the coil in this example is only 880 ohms, and the pickup weighs just over 200 g.

2. Lissen were a very active company in radio in the 1920s, marketing complete radios as well as components. They were bought out by Ever-Ready in 1929, but continued with their own marque. Their pick-up design is very commendable. At D1 is an adjustable suspension. The armature is large and flat, and passes close to the pole pieces of two coils. It is secured and damped at D2, and this damping is actually externally adjustable by means of the little knob on the outside of the case. Excellent stuff. The case is aluminium I suppose, so as not to draw any energy from the horse-shoe magnet, and also to save weight. The DC resistance is 2,100 ohms and the weight only 133 grams. Note that unlike the BTH and Woodroffe, which work radially, this device is mounted tangentially, like a normal acoustic sound box. The date must be the late 1920s.

3. Sidney George Brown (1873 - 1948) founded his company in 1903. It made scientific apparatus and was involved in radio from the start. S.G. Brown products were of great repute. This pick-up is for tangential mounting and is simple and elegant. The armature is mechanically pivoted under the bottom of the die-cast case, exactly like an acoustic sound box. At the top it is damped by rubber. There must be a gap between the pole pieces, behind the tapering portion of the armature. It was early in the field, as it was reviewed in the September 1927 ‘Gramophone’ magazine, along with the Woodroffe. The reviewer was slightly critical of the amount of ‘needle talk’ it produced, which he thought implied that record wear might be severe. Unfortunately, we have no price for it. The DC resistance of the coil is 1900 ohms, and its weight a fairly modest 141 grams.

4. Burndept was another long-lived radio company. This device, which works tangentially, is described on the front as ‘Electric Sound Box’ – evidently the old term persisted for some time. The suspension and the damping appear to be combined (always a good idea if possible) at the bottom of the armature, while the fish-tail moves between the pole pieces at the top of the coil; one is at the front left of the coil, the other at the right back. Exploring the design further would require dismantling the item, and now we are of mature years, we hold fast to the tenet: ‘If it isn’t bust, don’t fix it!’ Especially striking is the huge coil, so large that the front of the Bakelite case is shaped to accommodate it. Clearly the coil is wound with the usual very thin, almost hair-fine wire, for its DC resistance is a whopping 5700 ohms! The assembly is steadied inside the case by the strips of orange rubber. It weighs 156 grams. We have no definite date for this device, but probably circa 1930?

5. This unknown is clearly very small: less than 1.5" wide. But the front is missing and the coil is open circuit. The metal ring is actually the end of a tube about 1.25" long, which therefore sticks out of the back of the device, and was used for tangential mounting. The disc, I suspect, is a metal rod concentric with the tube, and fixed into the closed end of it. Therefore the poles of the magnet are the end of the tube and the end of the rod, with the coil filling in the gap between them? The armature is pivoted mechanically, like a sound box, and is damped right above the pivot by the pale orange rubber discs. The pressure on these can be varied by screws which come in from the sides. The top of the armature is simply a small flat disc. The disc is some distance from the end of the rod behind it, so something must be missing. The black housing appears to be ebonite. Any information would be welcomed, please! In its present state it weighs only 80 grams, which is practically nothing by the standards of the time – but when that time was, we have no idea…

6. The ‘Ajax’ surprises us by having no less than four coils. It’s a fascinating little thing. The armature is pivoted at the top, unlike most. The damping is the little tube just above the needle-grip. Two small headphone-like U-shaped magnets bear four coils, in a structure made of ‘jazzy’ black and brown Bakelite. Unfortunately, it is in very bad shape, the Bakelite on the left having cracked. At the extreme left is a vulcanised rubber tapered sleeve for mounting the device radially. This can be slid off, revealing a smaller mounting tube. The front and back plates are of ‘oxidised’ metal, black but coppery round the edges. They are help in place by four 8BA bolts & nuts, which pass through just inside the four corners of the case. In spite of its current dilapidation, it still works, and thus is crying out to be conserved. Wires connect to pillar terminals on top. The DC resistance is exactly 2000 ohms, and the weight a modest 92 grams. Though the box justifiably proclaims ‘British is Best’, it is reticent regarding the name of the company responsible for this very interesting product which cost 15/- (75p). Date? H’mm. early 1930s?

Class 1b pick-ups.

ese early electrical pickups enabled you to fix them on your old acoustic gramophone. Above you see the bakelite-cased ‘AED’ pickup in place on the same gramophone. The wire coming out of the back led away to whatever you were using to amplify the signal. Later, we’ll go into exactly what that apparatus might have been. This pickup was made by the AED company, probably around 1930 or a bit later. I’d hazard that the letters stood for ‘Acoustic and Electric(al) Developments’. The internal assembly is shown at the right, above. This is a horse-shoe magnet with a single coil. AED seems to have been a Limited Company belonging to an inventor & electronic developer called Bowyer-Lowe. (More on this below). Note the interesting Trade Mark stamped on the magnet; what is it? A fish?

Little was found on line about the next one shown above, which was made by a company called HEGRA. This might be because HEGRA, nowadays, is an acronym for High Energy Gamma Ray Astronomy, which – however intriguing the subject may now be – simply did not exist when the pick-up was made, probably around 1930. Besides which there is a Hegra hotel in Amsterdam, and also a place in Norway called Hegra. This has a bright nickel plated case and a very good wire to connect the output to an amplifier, which remains very flexible even 75 years since it was probably made. Doubtless it is what was called in English ‘tinsel wire’, which consists of a number of very fine copper or copper alloy ribbons which share the current. They are interwoven with cotton threads, which give flexibility and little risk of breakage. Even if one tiny ribbon somehow breaks, there are all the others still intact. Its internal structure is shown at the right. This HEGRA, too, has only one coil. One reason for these rather later pick-ups only having one coil might be that gradually, better magnetic materials were being developed for use in the horse-shoe, which provided the main magnetic field in these devices? It was certainly easier to manufacture such a single-coil pick-up.

But we have saved the best until last. And the reason is, that this beautiful, elegant and very early British J.B. Woodroffe pick-up of ~1927 (which disdains, in its simple dignity, to conceal itself in any casing) illustrates perfectly how these devices worked. As you can see, the needle was moved from side to

side by the lateral groove of the disc. The needle is mounted at the lower end of the ‘armature’ as it was called, and this armature is pivoted in its centre. The armature was made of iron, a magnetic material. The axis of this pivot is the set-screw which is visible in front of its brass locking ring. The position of the entire armature was also adjustable: this was achieved by the thick threaded rod you see, rigidly anchored to the right-hand arm of the horse-shoe magnet by the big nut on the right, the adjustment being secured by the knurled lock-ring on the inside. So: if the groove took the needle to the left, the lower end of the armature approached the core of the lower coil, inducing a current in it; while simultaneously the upper end of the armature would recede from the core of the upper coil, also inducing a current in it. (It is a change in a magnetic field, not the presence of a static field, which induces a current in a coil.) And because these two coils were wound in opposite directions, the voltages produced were added together. Two bites of the cherry, one might say! Movement of the armature to the right produced the converse situation, but which still produced a voltage. So all in all, the complex wave-form of the groove produced a corresponding voltage. Wires would have been connected to the two nickel-plated pillar terminals just below the signature trade-mark, and those wires would have been connected to our amplifier.

The other examples further up this page work in exactly the same way, though they only have one coil.

Before proceeding, we must address a very important point. Resonance. Any mechanical assembly has a resonant frequency. You have probably driven your car over those thickly-painted yellow lines across the road that are intended to make you slow up when approaching a traffic island? They often produce a distinctly unpleasant bumping up and down of your car – and you! Like anything else mechanical, your car has a ‘resonant frequency’, and those thick lines are designed to set your car’s suspension into resonance. Each stripe you drive over can add its impulse to the previous one, so that the resonance builds up, and tells you, in no uncertain way, that you really must slow down. For example, it seems that the resonant frequency of my car is about 5 or 6 ‘cycles per second’, or Hertz (Hz) as we now call them. It is a most disagreeable sensation to be vibrated up and down at such a frequency! A car is relatively big and heavy and so has a low resonant frequency. The smaller the mechanical system, the higher it is. So the resonant frequency of a small armature in an electric pick-up would be quite high. Several hundred Hz, possibly 1,000 Hz or so. The trouble is that this frequency is slap bang in the middle of the range where our music is. So our electric pick-up will produce a far higher output around this frequency than any other, because the vibrating armature ‘prefers’ to vibrate at (or even just near to) its resonant frequency, compared to all the others. This results in distortion of the music we want to listen to.

How can we make our electric pick-up ignore this particular frequency, and reproduce all frequencies evenly? Well, we must ‘damp down’ this resonant frequency. Actually, persisting with the motor car analogy, that it exactly what the shock absorbers on your car do. Otherwise, your car could easily begin jumping up and down from time to time in any case – not just when safety-stripes are painted on roads.

Here you see the other side of this Woodroffe pick-up, and all is obvious. The curly orange thing wrapped round the two slotted brass pillars is a strip of thick rubber. You can see the smaller screw-heads which anchor it to the pillars. What you can’t see (because it’s behind the yellow wires) is another screw which also anchors the rubber strip to the top of the armature. The purpose of this rubber suspension is to encourage the armature to respond equally to all frequencies, by preventing its tendency to resonate at its ‘preferred frequency’. I have looked at one or two other patent specifications for early pick-ups that can be found on line, and it would seem the method of suspension, or damping, is usually their main subject. After all, the basic idea of converting mechanical vibration into a voltage by a moving armature was really very old by the 1920s, so you couldn’t patent that. But you could patent a novel method of damping the armature – and that is what the inventors of subsequent ‘moving iron’ pick-ups usually seem to have done.

Very well. Now that we had our little audio voltage that corresponded to the music on our 78 rpm disc, what did we do with it? Why, we fed it into an amplifier. The output from this amplifier was connected to a loudspeaker, and Lo! the music poured out, refulgently, into our living room. But where did we get an amplifier in the late 1920s & early 1930s? If we were fairly prosperous in those times and had a radio set, then we already had an amplifier. The last valve (or two) in our radio set had the purpose of amplifying a small audio frequency voltage. True, that small voltage had been derived from the radio waves that our aerial had picked up; but one small audio frequency voltage is – generally speaking – much like any other small audio frequency voltage. So by the mid 1930s, most radio sets were equipped with ‘pick-up’ input connections on the back, and we plugged our wires into those.

However, if we were an ‘audiophile’ with a couple of weeks’ wages going spare, then we would construct a dedicated audio amplifier for our electric pick-up. Here is a circuit diagram for one. It came in a leaflet with another of these ‘add-on’ pick-ups, the ‘Phonovox’, manufactured by The Igranic Electric Co. Ltd. Unfortunately, the leaflet is not in good condition otherwise we would reproduce it in its entirety. But the circuit diagram speaks for itself. Naturally it uses all Igranic components, or at least all those necessary that Igranic made. The voltage from our pick-up goes into a step-up transformer. A volume control is connected across the secondary of this, which feeds into the grid of the first valve. The amplified signal passes via C1, the DC blocking condenser – ulps! capacitor I should have said – into the second valve. The signal emerges from this into another transformer, and proceeds thence to the output valve V3. The choke O.C. permits the high tension (DC) to reach V3, but prevents the audio (AC) from passing back that way; the audio therefore passes through C2 (which blocks the DC) to the Loudspeaker connections LS.

Note that several possible sets of valves are listed. The 2 volt range were of course for people who lived in houses where there was no mains electricity supply. If you are young, dear reader, you may be surprised to learn that there still existed large areas of this country, as recently as the late 1950s, which had no mains electricity! In such cases, you ran your radio set – and possibly even your Igranic gramophone amplifier – from a high-tension battery (up to 120 volts), and a 2-volt lead-acid accumulator to run the valve filaments. 4 volt & 6 volts valves ran from the AC electric mains via a step-down transformer. Notice there is no tone control. I’m sorry, if you wanted to blow the windows out of your house or drive your neighbours to distraction with ‘mega bass’, that simply was not possible around 1930! By the way, the three connections GB-1, GB-2 and GB-3 were connected to another battery, the ‘Grid Bias’ Battery, which was necessary to make the grids of the valves somewhat negative with respect to the incoming signal. That also is not important right now.

Another Class 1 pick-up with an interesting design feature was this ‘Radio Gram’. Who made these we do not know. The ‘cup sleeve’, which is simply fastened to the bakelite body by an eyelet, is of generous diameter, so it would have fitted most acoustic gramophone arms. The vertical screw drove down a simple U-shaped clamp which would secure the pick-up to the tone arm. The internal structure is quite simple, but featuring ‘tapering pole pieces’ (more on this far below). What is interesting about this one is the damping of the armature. In the third picture, you see screws which have two wire springs between them. This probably means that the armature is damped by these springs? This is analogous to the springs used on acoustic sound boxes. Remember, the armature requires both a suspension (a fulcrum), and also some damping to avoid resonance. Where the suspension is in this design is unclear; I prefer not to dismantle these things in order to find out. IF the suspension is the sort of rubbery disc around the needle hole, indicated by the yellow arrow, and which locates in a hole in the bottom of the bakelite (or ebonite?) casing… then, I think, we would have a truly novel pick-up! Namely, one which employed a Class 2 lever, as opposed to the Class 1 levers (a see-saw) that most of them use, and which, along with their unusual spring damping, would doubtless have been the principal subjects of the patents for which the makers had applied. (‘Pats. Pen.’ = Patents Pending.)

Even ‘Mighty HMV’ did not scruple to market a Class 1 pick-up. This one was called the ‘No. 11’, and came as an outfit, with connecting leads and volume control. Here it is seen in place on an Electrola gramophone, which is simply the German version of an HMV Model 109. This gramophone normally used the HMV No.4 sound box, and was current until the early 1930s (sorry I am so vague on the details of machines…) The point is, that the tone arm of the 109 was relatively small in diameter, so an adaptor sleeve is present in this example of the pick-up. HMV even thoughtfully provided a couple of chromium-plated clips, to keep the connecting wire from getting in the way. Incidentally, I would not dream of playing my rather nice OKeh of Frank Trumbauer’s ‘Borneo’ on an acoustic machine, still less with one of these extremely heavy electric pick-ups; it is simply there as a photographic ‘prop.’! 8^)

Above we see the black bakelite pick-up with its (rusty) securing screw. Then the internal structure: the usual horse-shoe magnet, the single coil and the red rubber damping at the top of the armature. This would have been very easy to replace. One assumes that the suspension of the armature was on the axis of the needle screw, and might have been the simple mechanical form. The coil is held in place by a couple of dollops of varnish. (See also the HMV No.15, dealt with in Class 2 below.) On the right is seen, we think, the complete outfit: the pick-up itself; its cable, terminating in a three pin plug; the volume control, which is a simple potentiometer (more on these below); another three pin plug on a much longer cable which led to your radio set. The plugs are not polarised, so will go in either way. This isn’t a problem, as we have here a ‘twin feeder’ with a separate earth in the middle. The letters on the input are: P – E – U. Pick-up, and Earth. Or Pick – Earth – Up, strictly speaking. The letters on the output side are B – E – C; E is clearly Earth, but what B & C are: who knows? Also, there are two of the chromium-plated ‘cable tidy’ clips, which we assume came with the outfit. If they didn’t, others would have hastened to supply them, as even to this day you can buy ‘cable tidies’ for the plethora of cables that lurk under your PC work station! I don’t use ’em myself; I tend to dismantle everything every four months or so, remove the now-redundant leads, stuff them in a drawer (you never know, they may come in handy some day – “Save The String” and all that), then vacuum up all the dust & cigarette ash that has gone down there. While this is a tedious procedure, it is also a most satisfying one, redolent of a Ritual Purification; and we all need one of those from time to time? 8^)

Addendum, 28th January 2011: I made a YouTube video of a No.11 in use! Just click: http://www.youtube.com/watch?v=0xFU5u07P8Q

I think that’s about it for our ‘Class 1’ pick-ups. There are of course many more waiting to turn up at car boot sales & on eBay, and as we acquire them, they will get illustrated & written up here. Accordingly, we now move on to:

Class 2 pick-ups.

That is, those which were marketed as an integrated pick-up and arm, mostly from the early 1930s onwards, which you could buy and fasten on to your acoustic gramophone, entirely replacing its acoustic tone arm – though I dare say, some people kept ‘hybrid’ gramophones, which would work either way!

1. The Bowyer-Lowe Mark IV.

This has British patent number 396,875, which dates to the early 1930s. Bowyer-Lowe had a company which made all manner of radio and electrical components. This arm is extremely well made. It rotates on a ball-race, and needs no ‘arm rest’, the front of the rotating bracket serving this purpose. The counterweight at the back is not adjustable, but balances the arm well. Changing the needle – which of course in those days you did after playing every record – was very convenient with this arm. You simply rotated the head 180º anti-clockwise, as seen below.

The internal structure is the now-familiar horse-shoe magnet, with a single coil in which the armature moves. The playing weight, as you see, was 95 grams, which was comparatively modest in those times.

Also illustrated here is a cardboard box which once contained a ‘Bowyer-Lowe’ “Beta” pick-up, with adaptor. We do not know what this ‘Beta’ pick-up was, though it may well have been the bakelite ‘AED’ one pictured above. What is interesting is that ‘AED’ and ‘Bowyer-Lowe’ are effectively synonymous. Possibly this may represent the inventor himself, Bowyer-Lowe, working through a Limited Company that would promote and sell his inventions, while leaving him free from the trammels of everyday business to pursue his researches?

2. The Meltrope Electric Pick-up and Arm.

This entry is being re-written – we had got it all wrong!!! <8^(

Wilson’s Meltrope pick-up embodied a still more revolutionary feature – it had no screw to hold its needle in place. Ever since gramophones had come into existence in the 1880s & 1890s, there had always been a screw to hold the needle in place. Evidently, Wilson would have none of this. He may have been trying to reduce the mass of the armature by getting rid of the needle-screw, which for durability, was made of iron & so increased mass? The less the mass of the armature, the higher its resonant frequency would be… and therefore, the easier to damp out & get rid of… Whatever his reasons, Wilson threw out 40 years of tradition and mounted his needles in aluminium collets. You can see in the pictures above, the thing the needle goes into is a metal tube. However, circa 1930, there were quite a variety of ‘gramophone needles’ in current use. Thin ones to play records quietly (they flexed more & transmitted less energy onto the pick-up); medium ones, which were… well, just medium; and loud ones, which were thick & rigid & sent more energy into the pick-up. [Here, an aside: gramophone needles were actually ‘pins’. A ‘needle’ has an eye, through which you thread your cotton, yarn or whatever, right? A gramophone ‘needle’ does not have an eye, and is therefore a pin. Accordingly, through all those years when countless billions of these were made, all the manufacturers duly referred to them, inside the factory, as ‘pins’.] But besides these, were non-metallic needles – which were much favoured by high-class gramophone enthusiasts of the time. These were the ‘fibre needles’, which reduced wear on records because they were softer than metal. There is no space here to go into all that sort of stuff. There is more than enough material in that subject for a Doctoral Thesis – indeed, I wouldn’t be surprised to learn that one or more has actually been written. If not, I commend it to you as a possible subject. The main point is that some (though not all) of these fibre needles were triangular in section. How then, was the Meltrope to cope with this great variety of thin, medium and thick steel needles, plus some triangular ones? The answer was absurdly simple: a range of at least seven collets was provided, as shown above. In order to take this photograph, I simply stood them up in a group, which was quite difficult as they kept falling over & rolling about. But oddly, they have turned out in some sort of order. The three on the left which have the smallest holes, are probably for thin, medium & thick steel needles. The two at back right are obviously for the triangular fibre needles, and the two at front right are probably for round non-ferrous needles – ‘thorn’ needles as they were called. Years ago, I tested thorns from a hawthorn hedge in the garden of my old house, and they worked quite well. In the United States these are referred to, for obvious reasons, as ‘cactus needles’. There is – or used to be – much lore on how to treat & prepare these thorns to render them more durable. At the risk of boring you to distraction, I quote below one recipe from “Gramophones – Acoustic and Radio”, ‘The Official Handbook of “The Gramophone”’, which dates from not before 1932.

A SUGGESTED DOPE FOR FIBRE NEEDLES.

The object of doping fibres is to make the points tougher so that they are less susceptible to breaking down in the heavy passages of a record, and so that the reproduction is cleaner and the volume slightly greater.

Make a saturated solution of Gum Arabic and water and a saturated solution of Potassium Bichromate and water. When the fibres are ready for doping—not before—thoroughly mix two parts of the Gum Arabic solution to one part of the Bichromate solution in a dark room and leave the needles in the mixture, also in the dark, for at least fourteen days. Then remove and wash the fibres lightly in water and wrap in a cotton duster to remove surface moisture. Allow the fibres to dry in the sunshine or any artificial ultra-violet light such as that used by draughtsmen for taking blue-prints, or even one of the domestic "sunshine" appliances now on the market. When the needles are absolutely dry clip and use in the ordinary way. But remember the "don'ts."

Don't mix the two solutions until the fibres are ready for doping.

Don't expose the mixture to light.

Don't dry the needles in front of a fire or in an oven.

The above is obviously commendable, even if it bears a distinct resemblance to mediaeval alchemy: the ritual of which was at least as important – indeed often very much more so – than the actual physical & chemical processes involved. I mean, if your 78 rpm records didn’t sound better after you had prepared your fibres or thorns in this time-consuming manner, then I really don’t know what to say. I am puzzled though, by the phrase: ‘When the fibres are ready for doping—not before—’ How did people know when the time was right? They do not tell us when this is; so it must have been common knowledge circa. 1932, but has since been lost to us. Did gramophiles of the time, lighting their after-breakfast pipe, stroll around the garden contemplating the primroses & hollyhocks, then after studying the sky for some time and possibly noting the propitious flight of certain birds, call back to the house: “Cynthia darling! It’s time to dope the thorns! Be a sweetie and mix up the Gum Arabic and the Potassium Bichromate, won’t you, eh? I’ll be in presently.”?

3. An Electrical Arm of Unknown Make…

This arm is interesting in that it seems to be designed specifically for the ‘side-fixing’ type of electric pick-up. That is, the ones that fitted into the pre-existing arm of an acoustic gramophone. Accordingly, it must be quite early. It also has a rather ‘scratch-built’ appearance, though there would have been a great deal of effort involved in this. It’s made of aluminium or some alloy thereof. There is no identifying mark or any kind on it. A clue, however, lies in the rather ‘weathered’ Woodroffe pick-up attached to it. This is firmly fixed in place by slight corrosion, and has defied all efforts to loosen it, even using WD40 & so on. I have given up trying, as something will undoubtedly break. The pick-up has clearly been fixed to the arm for a very long time. So, using Occam’s Razor, we have a very old arm, and a very old pick-up; so we must assume that they belong together. And in view of the absence of maker’s name, model or patent number, it’s either a prototype or a limited-run specialist arm. From the photograph at right you can see the arm pivot is simple in the extreme, but it works well. The merest drop of oil would keep it sweet. Adjustment of the playing weight is simple but effective. The knurled nut N is used to compress a spring which bears down into a hollow in the arm behind the arm pivot P. It is possible to get the playing weight down to zero so that the arm ‘floats’. Unscrewing the nut increases the playing weight. As with modern arms, one must be careful not to use too small a weight. A weight of around 100 grams (a quarter of a pound) may seem horrifically heavy to us today! But any attempt on the part of a 1930 gramophile to reduce this weight significantly would have resulted in the needle ‘chattering’ in the groove & so causing serious record wear as well as poor reproduction. The needle absolutely must bear down into the groove with sufficient force (but no more, to be sure) to enable the pick-up armature to be driven efficiently; and that is as true today as it was in 1930. When I worked in the domestic audio trade in the early 1970s, customers would sometimes proudly say they had persuaded the modest Shure M-44 cartridge to track at 0.75 grams. My reply needed some tact, because that weight simply wasn’t enough! The M-44 required about 1.5 or 2 grams (I forget now) to track properly, so they would be getting just the same sort of effect as our 1930 person. The term ‘needle chatter’ had been long obsolete, but increased wear on their LPs & a less focussed sound would still have occurred!

One thing which is very important about arms is their height in relation to the turntable. Traditionally, they have always been required to be parallel to the surface of the record. In the case of this arm, when it is level, there is only just over half an inch (~1.5cm) beneath the needle. This isn’t much to accommodate the height of an old-style turntable. It might have been necessary to mount the arm on a spacing block to raise it up. By the way, you can’t see the wires in this arm; the ends have been cut off. But it is ordinary ‘twin flex’, and runs under the arm which is, in effect, an inverted trough.

4. An important accessory: The Volume Control.

We have seen how these early pick-ups were connected to an amplifier, and that a volume control was needed. (R1 in the circuit diagram above) Even if we were plugging our pick-up into the back of a radio set (which usually – though not invariably – had a conventional volume control) another one might still be necessary because the pick-up could deliver too high a voltage into the audio amplifying stage(s), causing overload & hence distortion. One quite common pick-up arm, made by Harlie, cleverly incorporated a volume control into its pivot, the knob being on the top of it. Eventually we will obtain one of these & write it up. This has now been done – see 5 below… But if you just had an arm like those we have dealt with above, you would almost certainly need to purchase a volume control. This was simply a potentiometer: that is, a resistance which you could tap up and down in value by rotating a knob, which adjusted an arm (the wiper) which went around the track of the resistance - but a picture is worth a thousand words…

Left. A complete unit mounted in a bakelite housing, which you would (carefully) screw down in a convenient place. The wander plugs on the pick-up lead went into the two holes at the top, and the flying lead seen at top right would go into the radio set. This unit carries no maker’s name. These black knobs with the arrow were extremely traditional in the later 1920s & 1930s. Centre. A smaller, panel-mounting potentiometer, but still with a traditional knob. Right. The underside of the same device, which reveals that it was imported here from the U.S.A. Scratched into the casing lower right is “1/4 MEG” – that is, one quarter of a Megohm, or 250,000 ohms, the total resistance of the track. The devices illustrated here date from around 1930 – 1934 we think.

5. The Harlie Pick-up Arm.

As mentioned above, these sold well, and happily were able to acquire one, thanks to a helpful seller on eBay. The knurled knob is marked ‘Max – Min’, and the cable is tinsel wire, very flexible. This is a handsome arm with its pleasant contrast of bakelite and chromium plating. The ‘works’ are shown, and are just as we would expect by now. This arm probably dates from the early 1930s. One notable feature is the stepped laminations. (These are thin sheets of metal stacked & clamped together – magnetism is transmitted better by a layer of thin strips rather than a solid bar.) The brass nuts holding them tight are painted with a brown coating to stop them coming loose. Above the coil you see that each lamination is slightly longer than the one in front of it, and the only the longest one(s) come right up to the armature – you can just see this coming out of the centre of the coil. This is a good design feature, because the magnetic field from the horse-shoe magnet is concentrated just where it is needed – i.e., each side of the armature. We are very much in the Art Deco period at this time, and the bakelite front cover reflects this.

6. The Cosmocord Pick-up Arm.

The Cosmocord company were based in Enfield, Middlesex. The brand name ‘Acos’ was used by this company later on, and ‘Acos’ became ubiquitous in the 1950s, and for several decades after, with their crystal and ceramic pick-up cartridges, their styli and microphones, besides other products. This arm, again from the early 1930s I guess, is of quite light construction, and also embodies a volume control, this time alongside the pivot. As it a one-piece structure, provision has been made for the head to rotate clockwise to allow the easy changing of needles, as seen at the left. This pick-up has two plates, not laminated, which convey the magnetic field to the armature – although they are tapered to meet it, as in the Harlie above. Again, Art Deco Rules, as the bakelite front cover shows! In fact, there is a great similarity between this front and the front of the Harlie. A similarity which is almost disquieting when one comes to think about it. The insides are fairly different though; the damping in the Harlie seems to be applied to the top of the armature, while that of the Cosmocord is centred on the armature pivot. Still, one wonders whether Harlie made pickups for Cosmocord or vice versa!

7. The ‘Daptacon’ Pick-up Arm.

We acquired a ‘Daptacon’ pick-up head from the Ron Armstrong collection; this is illustrated right at the top of this page. At that time, we were not sure how it fitted into ‘the scheme of things’. But it turned out to be the detached head from a complete assembly, so really belongs in our Class 2. As you see, it is of simple structure, and so probably was budget priced. Also, you can only raise the arm to an angle of abut 40 degrees, and the head does not rotate for the fitting of the new needle, which means you have to more or less ‘fiddle’ the needle into the socket – unless you want to kneel down so that you can see what you are doing. The head itself is of all-metal construction, relatively unusual. It has not a horse-shoe magnet; instead, it has three separate bar magnets in an inverted ‘U’ shape. All these things, we feel, tend to indicate a date further into the 1930s than most of the other examples on this page. Let’s guesstimate 1934/6? Also, there is no provision for the lead to pass through the flange of the pivot. A hole would have to be drilled in the motor board, and the lead pass down to the radio chassis or amplifier. This again indicates a later date?

8. The Marconiphone Pick-up Arm.

Well, we have to say, that this picture is just as much about the box as about the arm! Resplendent in its Art Deco design and ‘chemical red’ colour, the box houses an example of what is probably the most ubiquitous pick-up arm of the mid and later 1930s. By this time, the ‘domestic audio’ side of Marconi was of course part of EMI, which principally included HMV and Columbia. This same arm was fitted to many EMI products. Each arm, whether HMV, Columbia or Marconi, would have borne that company’s logo on the top of the head. Unfortunately, that little ‘Marconiphone’ plate is missing from this example; but that’s not a problem really, as it will be fairly easy to acquire all these types in the future. Another thing that is missing is the arm rest. Some of the arms we have dealt with so far were ‘self-supporting’, but the ‘arm rest’ was gradually becoming obligatory. Again, that’s not important right now. Another sign that we are entering a later period, is the frequency response curve printed on the front flap of the box. Frequency response graphs had been around for many years of course, going right back into the acoustic era; but at that time they were intended for the specialist audiophile – or ‘gramophile’ as they were known in those early days. The fact that ‘the man in the street’ might know enough to be impressed by a frequency response curve, represents a significant change in the way equipment was being marketed… click here to see the curve.

At the left is the arm, looking a little floppy & folorn without its arm rest! Next is the underside of the pick-up. The head did not rotate, but the arm lifted up through a large angle so that fitting a new needle was quite easy – you could see what you were doing. Notice the five screw-holes: they are filled with a thick varnish or solution of shellac – much the same thing. This, we suggest, was not to stop the screws working loose by vibration (though it would have served that purpose), but as insulation to prevent dangerous voltages, up to 250 volts, appearing on the pick-up head. Many radio sets of the time had a ‘live chassis’, as it was called. Without going into detail about this, in some cases the mains voltage could appear on outlying accessories such as a gramophone pick-up. All five holes are here filled. This means that this pick-up has never been opened; or if it has been, the holes have been re-filled with insulating sealant. In any event, we undid the central screw, so you can see the ‘innards’ on the right. These are at an angle, but still consist of a horse-shoe magnet and the inevitable coil of fine wire. The red rubber can be seen, where it damps the upper end of the armature, just as in the HMV No.11 pick-up shown earlier. But there is a startling new feature here! There is ANOTHER coil above, held in place by a brass strip. What is this for? Well, I think it is there as a ‘hum-cancelling’ coil. When Class 1 pick-ups were fitted to acoustic gramophones, there was no problem with ‘AC mains hum’ being induced into the pick-up: those early turntables were usually driven by spring motors. But later, when turntables were driven by AC electric motors, there was a distinct possibility that the alternating magnetic field from those motors might reach the pick-up, the action of which, as we have seen, depends on a varying magnetic field. This ‘AC hum’ would combine with the musical signal from our record, and spoil it. So probably, this pick-up has an extra coil, which is there solely to ‘intercept’ this rogue AC hum. Above all, this coil would be wound ‘in the opposite sense’ to the main coil, so that the hum induced in the main coil would be cancelled out when their outputs were combined. Yes? Er… well, it’s not a bad suggestion; I must do some more research here….

9. The HMV No.15 pick-up.

This pick-up was an integral part of an arm, or even an early HMV ‘record deck’ – we are not sure yet – but has been detached, possibly to be kept as a spare part. You obviously turned over to change the needle; there are two ball catches on the brass sleeve, and a pin would engage the slot, and limit the travel. Incidentally, one of my great-grandfathers, Charlie Holder, invented the ball-catch. This was in Wolverhampton; the date is uncertain, but it was not after 1906, as he died in that year. His son (my grandfather Arthur Holder) told me that Charlie was working in a factory, and the owners patented it, and in recognition & compensation gave him a rise of a pound a week to pay him for this useful invention, and also any others he might make. This meant he got fifty shillings a week (£2.50) instead of thirty shillings (£1.50), an immense rise! Alas, the patent specification was very poor, and was easily circumvented by other companies. Worse still, the Trade Union in the factory objected to Charlie’s having so much more money when he essentially did the same work as they did. Accordingly, he went back to 30/- a week. Of course, there might have been some connivance between ‘union and management’ in the matter! One consequence of the affair I do know about, was that my grandfather Arthur, born 1882, was thereafter implacably opposed to Trade Unions – even though he himself spent his entire working life (1896 – 1957) on the shop floor. So he must have been a member of a Union – though reluctantly! Returning to our main topic, as you can see, the internal structure of the pick-up is virtually the same as the Class 1 HMV No.11 unit shown above. Ball park date? Say 1930?

Addendum, 28th January 2011. Two YouTube videos of a No.15 being partly restored, and finally working, may be seen at:

http://www.youtube.com/watch?v=yQAFGTm3fPI

http://www.youtube.com/watch?v=TPyD1NjPSpI

This is nominally the end of this page, with a couple of concluding paragraphs below. But as at February 2009, we are extending this page to cover two ‘home recording devices’ contemporary to some of the above items. We’re just ‘parking’ the following here temporarily – there will eventually be another page covering the various home recording devices we know of.

1. The Ekco ‘Radiocorder’ Home Recording Device.

This apparatus cost a whopping Five Guineas, (£5.25) back whenever it was around – which would have been, yet again, the early 1930s I should think. That was something like two weeks’ wages then? But still, you got quite a ‘chunky’ set of things for your money! It is obviously in quite good condition, but still needs a little restoration, which is why it can’t be assembled properly in this photo. In the background is the playback arm. The hollow cylindrical mount and the two thick pins locked into the bakelite mounting block on the right – the thing with the three little pillar terminals on it. This mounting block had a height adjustment bush – it’s being used here to prop up the back left of the recording assembly! To record, you unplugged the playback arm, and replaced it with the recording assembly. So the right hand end of the assembly was firmly anchored. The left hand end, with the rubber wheel, then rested somewhere near the centre of the turntable. As the turntable rotated, it drove the rubber wheel, which operated the horizontal feed-screw, and thus traversed the cutting head over the disc, which was of soft aluminium. I should have said that the same head is used for recording and playing. It has two long pins on the back of it, and so is interchangeable. About seven thousand words ago, I pointed out that the first telephones would act as a receiver or a transmitter; and so will these moving-iron pick-ups! Although in good condition, most of the cast parts are of ‘pot metal’, which in time expands, & the two cylindrical mounts have got too big to go into the base. It will be necessary to take them down a little with emery tape. On the left, above, is the inside of it and suddenly all is clear – it is identical to the Harlie pick-up shown above. The same reddish-brown lacquer to hold the nuts, the same laminations, the same damping – and of course the same style of front cover, albeit in tasteful mottled green bakelite. Look: here are all three covers together:-

The Cosmocord pick-up is different in structure, but it seems clear we have a common maker here. I wonder who it was? We shall have to find out.

2. The Harlie Home Recording Device.

This unit is slightly distressed, but its function is plain. We have called it a Harlie device because it has a Harlie head on the front, which is internally identical to the other Harlie & the Ekco. The transfer on the vertical pivot is currently illegible. Obviously, the loose pulley at left is secured to the centre spindle of the turntable with the little wing-nut. The flexible spring belt – like those on cine projectors – then drives a corresponding pulley in the base of the pillar. A bevel gear in turn drives the horizontal feed-screw. In due course it will be restored.

The End!

There follows two short paragraphs which will eventually be put back in their proper place.

By the way, what was the output in volts, of these early pick-ups *? What was their frequency response? And what was their impedance? Well, this page is long enough already. If you have read this far and have any interest in the subject, it will be easy for you to research these matters on-line! (As regards simple DC resistance, the Wodroffes are just over 2000 ohms. The others, with the single coils, range between 1000 & 1200 ohms)

As to what they sounded like, that’s another story altogether. All the rubber damping and suspensions of these units has become rock-hard after 80 years. If you played a record with one of these today, it would certainly damage your record. Moreover, magnetic materials have been vastly improved since those times, and these horse-shoe magnets will probably have lost a good deal of their field strength over the years, and the voltage output depends on the magnetic field. The only true evaluation of this type of pick-up would require re-magnetising of the horse-shoe to the same level as it had originally. How do we know what that was? I certainly don’t know. The logical assumption would be that they were magnetised to their saturation level, but even that would have to be checked out. Similarly, the damping/suspension rubber would need replacing by a material with exactly the same elastic properties as the original rubber. Which we can probably never know! Besides, what they sounded like would depend on what amplifier you fed them into, and above all, what sort of loudspeaker you used. No; I’m afraid the quest is rather useless, as is attested by the lack of general interest in these items. As I remarked at the top of this page, early electric pick-ups are, apparently, very much the ‘Cinderella’ of record-playing equipment! <8^(

* The frequency response chart of the Marconiphone, a link to which is given above, indicates that its output was all of 1.7 Volts at 0 dB. Hence the need for an intermediate volume control…

Page first uploaded 10th November 2008.

Revised 8th January 2009.

Revised 2nd February 2009.

Revised 5th April 2009.

Revised 29th January 2011.